Modern Traffic Light installations will include communication between the traffic light controllers and centralized back-end systems. Such connected traffic lights, also referred to as on-line traffic lights, will offer access to the present status of the traffic lights, i.e. the phases; red, yellow or green. On-line traffic lights also provide means to get access to the phase schedules, i.e. a scheme for the planned traffic light phase changes for a limited time window. Such traffic light data are often referred to as Signal Phase and Timing data or SPAT data. The SPAT data, once available in some back-end system, can be transmitted to vehicles to be used in in-vehicle applications, such as Time to Green countdown, GLOSA (Green Light Optimal Speed Advisory) to or Red Light Violation Warning. The SPAT data is however not sufficient but requires a complimentary information about the positions of the traffic light. More precisely, what road or lane traffic each traffic light is regulating. Such data are referred to as MAP data. In combination, the dynamic SPAT data and the more static MAP data will be sufficient data to enable connected traffic light functions.
The Chinese patent publication no CN102779415 (A) discloses a Method and device for real-time analysis of traffic signal phase. The traffic signal phase is analyzed using floating vehicle data such as the distances between stop points of the vehicles and traffic lights at the signal crossing intersection and/or the start and stop time of the vehicles.
However, there are problems associated with the use of this data for traffic light analysis applications.